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Calling 5 Twins, need jetting help

Discussion in 'The Garage' started by garyr, Oct 10, 2021.

  1. garyr

    garyr XS650 Enthusiast

    44
    27
    18
    NJ
    N8 (168) The needle itself is SF-21 Mike knew right away that set up was wrong. I have no clue, never had to change needle and needle jet.
     
    grizld1 and jetmechmarty like this.
  2. jetmechmarty

    jetmechmarty Project collector XS650.com Supporter Top Contributor

    650 Central is the most valuable business to this hobby. MikesXS has nobody AFAIK.
     
    arcticXS, grizld1 and garyr like this.
  3. garyr

    garyr XS650 Enthusiast

    44
    27
    18
    NJ
    :agree::cheers:
     
    arcticXS likes this.
  4. grizld1

    grizld1 Grumpy old man Top Contributor

    +1 to that! When Michael retires he's going to leave a huge gap.

    This thread has drummed a in a lesson for me: Don't generalize. The generic NJs in the VM carbs I'm used to working with on the XS650 have to be leaned out substantially to work at all well even on hopped up big bore motors, so I assumed that the N8s would be rich enough--and we know what happens when we do that. Stepping up NJs would have been the next suggestion after confirming fuel level, but Michael had the knowledge to prescribe needles and a range of jets without a bunch of rounds of cut-and-try.
     
    arcticXS and jetmechmarty like this.
  5. 5twins

    5twins XS650 Guru Top Contributor

    21,922
    15,470
    813
    Mikuni needle codes begin with a number, not a letter, so your needle is probably a 5F21. This first number in the code designates the length series in 10mm increments. A 5 series needle would be between 50 and 60mm long, a 6 series between 60 and 70mm etc. Normally, a longer (leaner) 6 series needle is used.
     
  6. hovel

    hovel ol' stupid XS650.com Supporter

    Nor at any of their "partners". They are strictly retail sales. When they sell you sub-standard goods and you call them down for it, they can be difficult to deal with.
    I wrote Mikes and DCC off long ago.
     
    grizld1 likes this.
  7. jetmechmarty

    jetmechmarty Project collector XS650.com Supporter Top Contributor

    I don't expect there will be any new parts or improvements to the ones in the catalog. Who could possibly do it?

    "Clean the communicator"
     
    Last edited: Oct 13, 2021
    Jim, Jan_P and grizld1 like this.
  8. hovel

    hovel ol' stupid XS650.com Supporter

    What we've got here is failure to commutate.
     

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